Wegovy for Weight Loss: How It Works, Dosage, Results, and Side Effects
Wegovy has been the reference point in medical weight management since 2021, and the picture has changed considerably in the last twelve months. There is now a higher-dose version approved, a liver disease indication, and four-year data showing the weight loss holds. This guide covers what Wegovy is, how it works, what the dose schedule looks like, what results the trials actually produced, and what to expect from the side effects.
What Wegovy is
Wegovy is Novo Nordisk's brand name for semaglutide at weight-management doses. It is a once-weekly injection, first approved by the FDA in June 2021, given alongside a reduced-calorie diet and increased physical activity.
It is the same molecule as Ozempic, dosed higher and licensed differently. Five years on, Wegovy holds a notably broad set of approvals:
- Chronic weight management in adults with obesity (BMI 30+), or overweight (BMI 27+) with at least one weight-related condition
- Adolescents aged 12 and over with obesity — approved December 2022
- Cardiovascular risk reduction in adults with established heart disease and obesity or overweight — approved March 2024
- Non-cirrhotic MASH with moderate to advanced liver fibrosis — approved August 2025
- Wegovy HD, a higher 7.2 mg dose — approved March 2026
That MASH approval made Wegovy the first GLP-1 medicine licensed to treat metabolic dysfunction-associated steatohepatitis, a progressive liver disease affecting an estimated 14.9 million American adults.
How Wegovy works
Semaglutide is a modified version of GLP-1, a hormone your gut releases after eating. The modifications let it stay active for about a week rather than minutes.
Its main effect on weight happens in the brain. GLP-1 receptors sit in the hypothalamus and brainstem — the regions that govern hunger and fullness — and activating them delivers a stronger, earlier satiety signal than a meal alone would produce. It also dampens dopamine responses in the brain's reward circuitry, which shifts not just how much people want to eat but what they want, reducing the pull of energy-dense food.
Two supporting mechanisms run alongside it. Semaglutide slows how quickly food leaves the stomach, extending fullness past the meal. And it prompts glucose-dependent insulin release — insulin when blood sugar is high, quiet when it isn't — which is why it improves metabolic markers without causing low blood sugar on its own.
The practical upshot is that this is not appetite suppression through stimulation or willpower. It is signal modulation, operating below conscious control. People typically describe hunger as absent rather than as something they are successfully resisting.
Wegovy dosage and the titration schedule
Wegovy is escalated slowly over four months. The schedule exists to let the digestive system adapt, and it is the single biggest factor in how comfortable the first few months feel.
| Weeks | Dose | Purpose |
|---|---|---|
| 1–4 | 0.25 mg | Tolerance step — not a treatment dose |
| 5–8 | 0.5 mg | Escalation |
| 9–12 | 1 mg | Escalation |
| 13–16 | 1.7 mg | Escalation |
| 17+ | 2.4 mg | Standard maintenance dose |
| Optional | 7.2 mg (Wegovy HD) | After ≥4 weeks tolerating 2.4 mg, where further reduction is clinically indicated |
Each step lasts four weeks before moving up. Some people stay at a lower dose if it is working well and tolerability is better there — the maintenance dose is not automatically the maximum dose.
Injections go into the abdomen, thigh or upper arm, on the same day each week, with or without food. Rotating the site each week helps avoid skin reactions.
What the results actually look like
Wegovy's evidence comes from the STEP programme — a series of phase 3 trials that established what this class of medicine could do.
STEP 1 is the headline trial: 1,961 adults with obesity or overweight and no diabetes, over 68 weeks. Average weight loss was 14.9% against 2.4% for placebo. Put differently, 86% of participants lost at least 5% of their body weight, compared with 31.5% on placebo.
Across STEP 1, 3, 4 and 8, average weight loss ranged from 14.9% to 17.4% in people without type 2 diabetes. Between 69% and 79% lost at least 10% of body weight, and 51% to 64% lost at least 15%.
STEP 2 looked at people who also had type 2 diabetes and found lower average loss — 9.6% versus 3.4% for placebo. This is a consistent finding across the field: weight loss tends to run smaller in people with diabetes, and it is useful to know in advance rather than to be surprised by.
STEP 5 extended follow-up to 104 weeks and found weight loss of 15.2% versus 2.6% for placebo — the effect held across two years rather than fading.
Real-world data has largely matched the trials. A US retrospective study of Wegovy 2.4 mg found 14.5% average weight reduction at 68 weeks, close to STEP 1's 14.9%, with 11.9% among those with higher baseline HbA1c.
| Trial | Population | Average weight loss |
|---|---|---|
| STEP 1 | 1,961 adults, no diabetes, 68 weeks | 14.9% (vs 2.4% placebo) |
| STEP 2 | Adults with type 2 diabetes, 68 weeks | 9.6% (vs 3.4% placebo) |
| STEP 5 | 104-week follow-up | 15.2% (vs 2.6% placebo) |
| STEP TEENS | 201 adolescents aged 12–17, 68 weeks | 16.1% BMI reduction (vs +0.6% placebo) |
| STEP UP | 1,407 adults, 7.2 mg dose, 72 weeks | 20.7% |
Wegovy HD: the 7.2 mg dose
The FDA approved Wegovy HD on 19 March 2026, with a US launch the following month. It is the highest semaglutide dose licensed for weight management, and it is intended for people who have tolerated 2.4 mg for at least four weeks and need further weight reduction — not as a starting point.
The evidence comes from STEP UP, which enrolled 1,407 adults with obesity and no diabetes and ran for 72 weeks, comparing 7.2 mg against 2.4 mg and placebo. Results were published in The Lancet Diabetes & Endocrinology in November 2025.
- Average weight loss of 20.7% on 7.2 mg, against 17.5% on 2.4 mg among adherent participants
- One third of participants on the higher dose lost 25% or more of their body weight
- 89% achieved at least 5% weight loss, versus 38% on placebo
A follow-up analysis presented at the European Congress on Obesity in 2026 looked at early responders — people who had lost 15% or more by week 24. In that subgroup, average weight loss reached 27.7%. MRI data showed 84% of the weight lost was fat mass, with abdominal fat down roughly 30%. That body composition detail matters, because "how much of this is muscle" is one of the most reasonable questions people ask about rapid weight loss.
Side effects at the higher dose follow the same pattern as 2.4 mg, with somewhat higher rates. One to know about: dysesthesia — altered or unusual skin sensation — was reported more often on Wegovy HD than on 2.4 mg or placebo.
Wegovy at a glance
- 14.9% average weight loss at 68 weeks on 2.4 mg (STEP 1)
- 20.7% average weight loss at 72 weeks on 7.2 mg (STEP UP)
- 16.1% BMI reduction in adolescents aged 12–17
- 4 years of sustained weight loss in the longest follow-up
- 5 approved indications — weight management, adolescents, cardiovascular risk, MASH, and the HD dose
Keeping the weight off
STEP 4 was designed to answer the maintenance question directly. Participants took semaglutide openly for 20 weeks, reaching an average 10.6% weight loss, then were randomly assigned either to continue or to switch to placebo.
Between weeks 20 and 68, the group that continued kept losing. The group switched to placebo gained. The difference between them came to 14.8 percentage points. Those who continued also held onto improvements in blood pressure and waist circumference.
The framing that follows from this is straightforward: Wegovy is maintenance therapy for a chronic condition, not a course of treatment with a finish line. The same is true of medicines for blood pressure or cholesterol, and nobody finds that surprising — the expectation that weight medication should be temporary is a holdover from thinking of weight as a behaviour rather than a physiology.
The longer-term news is encouraging. In the four-year SELECT follow-up, weight loss continued for roughly 65 weeks and then held steady through 208 weeks. The plateau is the body settling at a new equilibrium, not the drug wearing off.
Side effects and what to expect
Almost all of the side effect picture is digestive, and almost all of it concentrates in the titration period.
The most common are nausea, diarrhoea, vomiting, constipation and abdominal pain. At the 2.4 mg weight-management dose these run higher than at Ozempic's diabetes doses — roughly four in ten participants in STEP 1 reported nausea, against fewer than two in ten on placebo. Headache, fatigue, dizziness, hair loss and flatulence also appear on the list.
The pattern is predictable:
- Symptoms peak in the first two to four weeks at each new dose level, then settle as the body adapts
- Most are mild to moderate and transient — people describe food aversion more often than acute sickness
- The titration schedule is the main tool for managing them; compressing it reliably makes things worse
Practical measures help more than people expect: smaller portions, eating more slowly, stopping at the first sign of fullness, easing off very fatty or very rich food during escalation weeks, and keeping fluids up. Most digestive side effects respond to mechanics rather than endurance.
Adolescents in STEP TEENS reported gastrointestinal effects at similar rates to adults, generally mild or moderate and short-lived.
Who Wegovy isn't for
Semaglutide carries a boxed warning for thyroid C-cell tumours, based on rodent studies. Human relevance remains undetermined, and no confirmed human cases have been attributed to the drug in clinical trials. The warning translates into a narrow, specific exclusion rather than a broad caution.
Wegovy is not used by anyone with a personal or family history of medullary thyroid carcinoma, anyone with Multiple Endocrine Neoplasia syndrome type 2, or anyone with known serious hypersensitivity to semaglutide.
Common thyroid conditions are not on that list — Hashimoto's, Graves' disease, hypothyroidism on levothyroxine and benign nodules all sit outside it.
Some situations call for a conversation first rather than a hard stop: a history of pancreatitis, gallbladder disease, existing diabetic retinopathy, and any regimen already containing insulin or a sulfonylurea, since those doses usually need adjusting. Wegovy is also not used during pregnancy or while trying to conceive.
Wegovy vs Ozempic vs Zepbound
| Wegovy | Ozempic | Zepbound | |
|---|---|---|---|
| Molecule | Semaglutide | Semaglutide | Tirzepatide |
| Targets | GLP-1 | GLP-1 | GLP-1 + GIP |
| Maintenance dose | 2.4 mg, or 7.2 mg HD | 0.5–2 mg | 5–15 mg |
| Primary licence | Weight management | Type 2 diabetes | Weight management |
| Average weight loss | 14.9% at 2.4 mg; 20.7% at 7.2 mg | Lower — dosed for glycaemic control | 20.9% at 15 mg |
The head-to-head comparison people usually cite is SURMOUNT-5, where tirzepatide produced 20.2% average weight loss against 13.7% for semaglutide at 2.4 mg over 72 weeks. Worth noting that this predates Wegovy HD — the 7.2 mg dose has not been compared head-to-head against tirzepatide, and its 20.7% figure narrows the gap considerably.
Wegovy also carries indications tirzepatide does not: adolescents from age 12, and MASH with liver fibrosis.
Semaglutide in research settings
Beyond its clinical use, semaglutide is among the most actively studied molecules in metabolic science. Current research spans reward and craving circuitry, inflammation, liver fibrosis, kidney physiology and neuroprotection — the mechanistic findings described earlier in this article came from exactly that kind of work.
Research-grade material supports that laboratory context, and the standard that matters most is verification. Peptide identity and purity cannot be assessed by eye, which is why independent third-party analysis is the baseline for credible research supply rather than an optional extra.
Every compound in our catalogue ships with third-party testing, published openly in our COA database — including semaglutide, tirzepatide and the triple agonist retatrutide. These compounds are cold-chain sensitive, so storage and handling conditions matter alongside the certificate itself.
Explore the metabolic research category
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View metabolic peptidesFrequently asked questions
How much weight can you lose on Wegovy?
In STEP 1, average weight loss was 14.9% of body weight over 68 weeks at the 2.4 mg dose, with 86% of participants losing at least 5%. On the newer 7.2 mg dose, STEP UP found an average of 20.7% over 72 weeks, with one third losing 25% or more. Results are lower on average in people who also have type 2 diabetes — around 9.6% in STEP 2.
How long does it take Wegovy to work?
Appetite changes usually begin within the first few weeks, but meaningful weight loss builds over months. The dose takes 16 weeks to reach 2.4 mg, and the trial endpoints were measured at 68 to 72 weeks. Weight loss typically continues for around 65 weeks before levelling off.
What is the difference between Wegovy and Ozempic?
Same molecule, different doses and licences. Wegovy runs at 2.4 mg (or 7.2 mg for Wegovy HD) and is licensed for weight management, adolescents, cardiovascular risk reduction and MASH. Ozempic runs at 0.5–2 mg and is licensed for type 2 diabetes plus cardiovascular and kidney outcomes.
What happens if you stop taking Wegovy?
Weight tends to return. In STEP 4, people who switched to placebo after 20 weeks gained weight over the following months while those who continued kept losing — a difference of 14.8 percentage points. Wegovy is designed as ongoing maintenance therapy rather than a fixed course.
How long do Wegovy side effects last?
Digestive side effects peak in the first two to four weeks after each dose increase and then settle as the body adapts. Most are mild to moderate. Following the four-week titration steps rather than compressing them makes a substantial difference to how the escalation period feels.
Is Wegovy approved for teenagers?
Yes, from age 12, since December 2022. In the STEP TEENS trial, adolescents saw a 16.1% average BMI reduction over 68 weeks compared with a 0.6% increase on placebo, and 73% lost at least 5% of body weight. Nearly 45% moved into the normal weight or overweight BMI category.
Is the weight lost fat or muscle?
MRI data from the STEP UP early-responder analysis found 84% of weight lost was fat mass, with abdominal fat down roughly 30%. Resistance training and adequate protein intake are generally recommended alongside any substantial weight loss to help preserve lean mass.
The bottom line
Wegovy set the benchmark for medical weight management in 2021 and has kept widening since. The standard 2.4 mg dose produces around 15% average weight loss; the new 7.2 mg dose pushes that above 20%, with a third of people exceeding 25%. Four-year follow-up shows the loss holds. And the licence now stretches well past weight itself, into cardiovascular protection, adolescent obesity and liver disease.
The consistent thread through the evidence is that this works as ongoing therapy rather than as a fixed course, and that the titration period is worth taking slowly. Both are practical points more than cautionary ones.
For a closer look at how each compound in this class compares, our Info Center covers them individually, and the metabolic category groups them by research application.
Wegovy®, Wegovy® HD and Ozempic® are registered trademarks of Novo Nordisk A/S. Zepbound® and Mounjaro® are registered trademarks of Eli Lilly and Company. Peptides Costa Rica is not affiliated with, endorsed by, or sponsored by these companies, and does not sell these branded products. This article is provided for educational and informational purposes only. It is not medical advice, and it is not intended to diagnose, treat, cure or prevent any condition. Semaglutide is a prescription medicine and should only be used under the supervision of a licensed healthcare professional. Products offered by Peptides Costa Rica are intended strictly for laboratory research use only. They are not approved or licensed by the FDA for the prevention, diagnosis, treatment or cure of any disease. Not for human or veterinary use.
